1. Field of the Invention
This invention relates generally to the field of neural networks used for character or symbol recognition. More particularly, this invention relates to a method and apparatus for recognition of characters or symbols which are rotated, as for example around the center hole of a compact disk or in a circular arrangement on a can or bottle.
2. Background of the Invention
Character recognition is an important application of neural networks. Character recognition applications are used for recognition of text in documents as well as recognition of symbols and characters in industrial applications. In all applications, optimal accuracy in recognition of the characters is of great importance. An overview and background treatment of the various factors affecting neural network performance and training can be found in a paper entitled "Foundations of Neural Networks" by Patrick K. Simpson, published in Artificial Neural Networks: Paradigms, Applications and Hardware Implementations, edited by Sanchez-Sinencio et al., IEEE press, 1992, USA.
In conventional neural networks, both hardware and software, characters are recognized by providing a representation of the character to a neural network. Internal weighting functions are used to produce an output representative of the most likely character based upon a training process for training the network. Improving the quality of the training process is the subject of a large body of current research and currently determines the accuracy with which the neural network can identify the characters. In industrial applications, correct recognition of characters representing, for example, serial numbers can be critical to production control.
In some instances, serial numbers, alphabetical or numerical characters, graphic symbols, bar codes, or other characters to be recognized, are provided in a circular arrangement. An example of this is the serial number which is commonly found around the central aperture of a compact disk. Correct reading of such characters is substantially more complex than reading characters in a linear arrangement. The present invention seeks to enhance reading such characters by providing a technique for rearranging the characters in a linear arrangement, segregating and centering the characters.